login.py

# login.py
from __future__ import annotations

import os
import threading
import logging
from typing import Optional

from dotenv import load_dotenv
from huggingface_hub import login as hf_login

_logger = logging.getLogger(__name__)


class HuggingFaceLogin:
    """
    Lightweight, idempotent wrapper around Hugging Face Hub login.

    - Reads token from environment (.env supported).
    - Safe to call authenticate() multiple times (thread-safe).
    - Avoids writing to git credential store by default.
    """

    _env_loaded = False
    _env_lock = threading.Lock()

    def __init__(
        self,
        token: Optional[str] = None,
        *,
        read_dotenv: bool = True,
        add_to_git_credential: bool = False,
    ) -> None:
        # Load env only once per process (thread-safe)
        if read_dotenv:
            with self._env_lock:
                if not self._env_loaded:
                    load_dotenv()
                    self.__class__._env_loaded = True

        # Accept explicit token or fall back to common env vars
        self._token = token or self._read_token_from_env()
        if not self._token:
            raise ValueError(
                "Hugging Face API token not found. "
                "Set one of HF_TOKEN / HUGGINGFACEHUB_API_TOKEN / HUGGINGFACE_TOKEN in your environment "
                "or pass token=... to HuggingFaceLogin()."
            )

        self._add_to_git_credential = add_to_git_credential
        self._did_authenticate = False
        self._auth_lock = threading.Lock()

    # -----------------------
    # Public API
    # -----------------------
    def authenticate(self) -> bool:
        """
        Perform a one-time login to the Hugging Face Hub.
        Safe to call multiple times (no-op after first success).
        Returns True if authenticated in this call or previously.
        """
        if self._did_authenticate:
            return True

        with self._auth_lock:
            if self._did_authenticate:
                return True

            # Perform an in-process login; do not persist to git credentials by default
            hf_login(
                token=self._token,
                add_to_git_credential=self._add_to_git_credential,
            )
            self._did_authenticate = True
            _logger.info("✅ Authenticated with Hugging Face Hub.")
            return True

    @property
    def is_authenticated(self) -> bool:
        return self._did_authenticate

    # -----------------------
    # Helpers
    # -----------------------
    def _read_token_from_env(self) -> Optional[str]:
        # Check common env var names in order of preference
        for key in ("HF_TOKEN", "HUGGINGFACEHUB_API_TOKEN", "HUGGINGFACE_TOKEN"):
            val = os.getenv(key)
            if val and val.strip():
                return val.strip()
        return None